Sludge and refuse disposal



Oct. 4, 1949. w. s. MARTIN 2,483,918

' SLUDGE AND REFUSE DISPOSAL' Filed Oct. l5, 1946 4 Sheets-Sheet 1 Wr/w1 .si Mar/f1 'N I HY TTOR NE Y Oct. 4, 1949. w. s. MARTIN SLUDGE AND REFUSE DISPOSAL 4- ShetS-Sheet 2 `Fi1edv00t. 15, 1946 h. uw,

Oct. 4, i949. w. s. MARTIN' 2,483,918

SLUDGE AND REFUSE DISPOSAL Filed Oct. l5, 1946 4 Sheets-Sheet 3 /ITTORNEY w. s. MARTIN 2,483,918

SLUDGE AND REFUSE DISPOSAL 4 Sheets-Sheet 4 Oct. 4, 1949.

Filed oct. 15, 194e Patented Oct. 4, 1949 SLUDGE AND REFUSE DISPOSAL Warren S. Martin, Massapequa, N. Y., assigner to Morse Boulger Destructor Company, New York, N. Y., a corporation of Delaware Application (bctober 15, 1946, Serial No. 703,430

13 Claims.

This invention relates to the disposal of sewage sludge, refuse, rubbish, garbage and other like Waste material capable of being incinerated.

It is an object of the invention to provide apparatus in which rubbish including garbage or sewage sludge may be economically incnerated and the apparatus is such that either or both may be disposed of in the same furnace.

Sewage sludge consists of the residue which remains after the treatment of sewage by septic tanks, bar screens and mesh screens, by plain sedimentation or by other treatment. Even though ltered, it still contains substantial amounts of water. In this condition it is not combustible but it can be further dried by the application of heat and suiiciently desiccated so that it may be burned. Moreover, there is inherently contained in the sludge combustible organic matter having caloriiic value. Various suggestions have been made for drying and burning the sludge but most of these suggestions have not resulted in sufficiently eiiicient disposal to warrant their use.

In those communities where there is suicient sewage to warrant the installation of plants to treat the sewage for final disposal, there is also available other waste material, which must be disposed of, consisting of rubbish Such as waste paper, garbage and other cast off waste material.

It is an object of my invention to provide an apparatus of novel construction wherein a single furnace may be utilized to dry and then burn sewage sludge and also simultaneously to dry and then burn rubbish in such manner that all oi the caloriic value of the organic matter contained in both the sludge and the rubbish is taken advantage of whereby the nal disposal of both sludge and rubbish may be accomplished in an economical and efficient manner.

According to one embodiment of my invention I provide a furnace having a cylindrical charge drying and burning chamber having in its upper Zone a rotatable annular hearth onto which sludge is charged and given a preliminary drying and having in its lower Zone an annular hearth having associated therewith a mechanically driven rotatable stoker and a grate. Rubbish is charged into the lower zone, dried and burned there along with the sludge which has been previously dried in the upper zone. The dried or partially dried sludge is automatically moved from the sludge drying hearth into the rubbish burning zone. A combustion chamber connects with both the upper and lower zones of the furnace. The combustion chamber insures complete combustion of combustible fumes and gases and the hot combustion gases pass to a chimney. In their travel to the chimney the hot combustion gases come in contact with a heat exchanger Fig. 1 is a view in elevation and cross-sectionA of a plant embodying the invention;

Fig. 2 is a plan view of the furnace on line 2-2 of Fig- 1; g

Fig. 3 is a partial View in cross-section to larger scale of the sludge drying .zone of the furnace showing the sludge charging device and means for driving the rotatable hearth;

Fig. 4 is a partial View in cross-section of the burning zone or rebox showing the arrangement of the mechanically driven stoker;

Fig. 5 is a partial plan view, partly in crosssection, on line 5 5 of Fig. 4;

Fig. 6 is a partial plan view partly in crosssection on line 6--5 of Fig. 4; and

Fig. '7 is a view in cross-section and more or less diagrammatic of a modiiied form of sludge charging arrangement.

Referring to the drawings (Fig. 1), the apparatus, as shown, comprises in general a furnace A of cylindrical shape, connected to a combustion chamber B in turn connected to a breeching C. riihe furnace is provided with a rubbish charging hopper and chute D, a sludge charging device` and port an ash discharge chute F, a mechanically driven rotatable annular hearth G, a stationary annular hearth H, a charge burning grate J, a mechanically driven stoker K, and a' heat exchanger L. The breeching C connects with a chimney (not shown).

Referring to the drawings in further detail, the

furnace has a reboX i0 having a cylindrical Vsur.

rounding Wall il the upper end of which tapers inwardly in the shape of a truncated cone I2 forming an outlet or throat I3 from the iirebox lll into the sludge drying Zone I4. The sludge drying zone or chamber I4 is in effect superimposed on the rebcx I and has a surrounding cylindrical steel casing I8. The steel casing has a side wall I5, a roof I6 and an annular bottom wall I'I.

The rebox I0 connects with the combustion chamber 20 through a flue 2I having an adjustable damper 22 (shown conventionally) and the sludge drying chamber I4 connects with the combustion chamber 2li through an upper flue 23 having an adjustable damper 24 (shown conventionally) The combustion chamber 2! connects with a chimney (not shown) through a breeching 25 in which is a heat exchanger 26. It will be understood that the ues and combustion chamber are of standard construction lined with firebrick and are built according to good engineering practice.

The rebox is encased by a steel shell 30 lined with a suitable refractory 3| such as rebrick and the tapered portion I2 terminating in throat I3 is of refractory material. Also, the roof of the sludge drying chamber I4 is lined with refractory material 32 and also its cylindrical side wall is lined with refractory I9. The tapered throat portion is supported on the cylindrical side wall II of the rebox and its upper edge has an inverted V shape as shown at 34 which terminates short of a circular Y-shaped angle iron 35. This angle iron is secured to the rotating hearth as described hereinafter. It may be noted here, however, that the arrangement is such as to provide an annular air passageway 35 from the annular chamber 36 within the steel shell I8. Thus air may pass through the port 21 into the chamber 36 and then through the passageway 35 into the sludge drying chamber I4. This aids in preventing the underside of the rotating hearth 3'! and its associated mechanism in the chamber from becoming overheated.

In the lower part of the rebox is provided a stationary annular hearth 40 surrounded by an annular grate 4I between the outer periphery of the hearth and the inner periphery of the cylindrical side wall II. Within the rebox Ill is a mechanical stoker 42 the details of which are described hereinafter.

Below the grate 4I is an ash chamber or pit 43 which is enclosed by a wall 44 in the shape of an inverted truncated cone. It comprises a steel plate 45 lined with rebrick 45 and has a discharge chute 41 provided with a slide closure gate 48 (shown conventionally). This ash pit -wall may be supported by an angle iron 50 secured to the framework supporting the furnace, it being understood that the entire apparatus is carried by a suitable steel frame. I-beams I and 52 and columns 53 and other steel frame members not shown, all tied in together according to good engineering practice, support the weight of the structure.

'I'he stoker, designated generally by reference character 42, is supported on suitable structural steel members which are in turn supported by the side walls of the furnace. As shown in further detail in Figs. 4, 5 and 6, there is provided two main lbox beams 54 and 55 each of which comprises a pair of channel irons with the edges of their flanges welded together to form an air conduit. Thus, channel irons 56 and 51 are secured to each other to form the box beam 55 in which is conduit 58. Channel irons 59 and 63 form the box beam 54 and air conduit 6I. The ends of these box beams are anchored in the side walls of the furnace, it being noted that the ends 62 and B3 are closed off and ends 64 and $5 are not closed o. Consequently, the conduits 58 and 5I connect with an air port 66 in the wall of the furnace. This port 66 connects in turn to an air conduit 51 from the heat exchanger 26. It is to be noted that the space in port 66 between the ends 64 and 65 of the box beams 54 and 55 is closed olf by a stopper 'IB comprising a steel plate frame 'II and firebrick liner 12. Above and adjacent the port B6 is an upper air port 'I3 connecting with the ash chamber 43 and this port also connects with air conduit E'I. A damper I4 in port 66 and a damper 'I5 in port 'II-3 provide means for regulating the amount of air entering the ash chamber 43 and the air conduits 58 and 6I from the main air conduit 61 leading from the air heater 26. Air passing through conduits 53 and 6I passes into the stoker air chamber through apertures SI, 82, 83 and 84 in the webs of channel irons 5'I and 59.

To provide a suitable framework for supporting the Stoker 42 on the box beams 54 and 55 there are short cross beams secured to these beams, a channel iron 85 and a short box beam 85. The square frame comprising the beams 54, 55, 85 and 83 provides means not only to sup. port the Stoker 52 but also a suitable structural frame to support the main frame radial members 81 which hold up the hearth I0 and the grate lll. This hearth supporting frame comprises four upright angle irons 38 capped by a frame 'I8 made of angle irons.

Depending from the frame provided by the beams 54, 55, 85 and 85, is a pan 89 having tapering side walls and flat bottom 9|. This provides a closure for the bottom of the stoker air chamber 8B and it has an access door 92.

The stoker 42 is carried on a stationary hollow post S3, the lower end of which rests upon the bottom wall Si of pan G9. This prevents sidewise movement of the post 53. The main weight, however, is borne by radial webs 94 which are secured at their inner ends to the post and at their outer ends to the frame comprising the beams 54, 55, 85, and 85. The post 33 is made in two parts. The upper part is secured to the lower part by a threaded coupling 95. The upper part of the post provides means to support a stationary Christmas tree tuyre head 79 which consists of a plurality of progressively smaller truncated domes 95, El, one above another and capped with a dome cap 38. Each of these domes is open at its top and bottom and secured to the post by radial arms secured to a ring 99 in turn bolted to an annular shoulder |30 on the post. The cap 58 is removably mounted on top of the post. It will be noted that thesel stationary domes and cap are hollow and are spaced apart to provide annular` air ports IGI, H32 and |03.

Beneath. the stationary tuyre head, designated generally by reference character "I9, is a rotatable hollow truncated dome I M lwhich is supported by and rotates with a depending hollow spider sleeve. The spider sleeve comprises an outer sleeve IUS and the inner bearing sleeve I0'I concentric therewith, the two sleeves being connected by radial web arms |58. The bearing sleeve Illi rotates on a thrust bearing IOS, which, as shown, is of the ball bearing type. This bearing 59 is supported on an anular shoulder H5 secured to the stationary post 33. The bearing sleeve, having bearing surfaces EI I and IIZ, rotates about the stationary post 33.

The hollow sleeve 35 is secured at its upper end t0 the lower wall of the dome I 04 by bolts I I3.

wamsA Secured also to the hollow sleeve |06 is an annular flat ring ||4 having depending from its outer periphery a cylindrical ring I I5. vThe lower end of this ring l I 5 rotates in a circular channel IIS secured to the box beams. The channel IIS carries a pulverulent refractory material ||1 to form an air seal. Consequently, the stoker air chamber 90 is enclosed and connects through the hollow spider sleeve |06 to the interior of the hollow rotatable dome |04 and the stationary Christmas tree tuyre head 19. A stationary baille I I8 secured to the post 93 by a bracket ||9 provides means to adjust the relative amounts of air enter-V ing the tuyre head 19 and the rotating dome |04. This baffle is in the form of an inverted truncated cone.

Secured to and extending outwardly from the rotatable hollow dome |04 are a plurality of rearwardly curved hollow stoker arms |20, which rotate with this dome in the direction of the arrow |31. The interiors of arms |20 connect with the interior of dome |04. Each of the stoker arms has an upwardly and rearwardly inclined forward face 2| and a downwardly and rearwardly inclined trailing wall |22. The trailing wall is provided with air ports |23 through which air is supplied to a pile of charge |24 on the hearth 40.

The lower end of the sleeve |06 has bolted thereto a bevel gear ring |25 which meshes with a bevel `pinion |26 xed to the inner end of a rotatable drive shaft |21. The drive shaft |21 is mounted to rotate in bearings |28 and |29 in a casing pipe |39. This pipe I 30 extends through suitable apertures in the webs of the box beam 63,.it being noted that the double channel or box beam 86 provides ample strength to Support the bearing |28. The outer end of the pipe |30 extends through an aperture in the steel casing 30 of the cylindrical furnace and it is provided with a flange |3I to support a hollow flanged stuffing gland sleeve |32 to provide a stuffing gland for the hollow pipe |30. The drive shaft |21 has an outer end portion |33 of reduced diameter which is connected through a clutch |34 to the drive shaft of a speed reducer |35 which is driven by suitable means such as a pulley |36 connected to be driven by a prime mover such as an electric motor (not shown).

It will be understood from the foregoing description that rotation of the drive shaft |21 through the speed reducer |35 will rotate the gear ring |25 which in turn will rotate the rotatable dome l0@ with its stoker arms |20 which are secured to it. In practice the stoker dome is rotated relatively slowly-of the order of ve to ten revolutions per hour.

Means are provided to lubricate the bearings of the mechanical stoker and its driving mechanism. An oil cup |43 is connected to the interior of casing pipe |30. Lubricating oil enters the pipe and will find its way to bearing |29 and bearing |28 and also to pinion gear |26. A drip pan |4| will catch oil that may drip from the pinion gear |26. Another oil cup |42 provides oil for the bearings on post 93. It is connected by a tube |43 running through the box beam 55,

through the air port 84 and thence upwardly up through the hollow post 93 to a union connection 44 connecting to an oil duct to bearing I I2. The lubricant will gravitate from the cup |42 and through the tube |43 and find its way to bearing ||2 and then down the outside of hollow post 93 to bearings II I and |09. The union- |44 is accessible by disconnecting the threaded coupling Referring now to the upper part of the furnace (See Figs. 1, 2 and 3), there is provided a rotatable annular hearth designated generally by reference character 31. This hearth has a lloor |50 of refractory material carried on a steel plate ring |5I, which rests upon a circular channel iron track |52 and is reinforced by a plurality of Web'brackets |53. The track |52 rides in a plurality of circumferentially disposed flanged rollers |54 of which, as shown, there are eight, each mounted for rotation in a clevis or yoke |55. These roller supporting yokes are mounted so that the overlying weight is supportedlby a plurality of steel columns 53 circumferentially spaced around the furnace and comprising a partY of the structural frame. Only one of these columns is shown in the drawings to avoid cbscuring other parts.

To rotate the sludge drying hearth 31 about the vertical axis of the furnace a chain |56 is trained around the channel track |52 and driven pulley |51. Grip lugs may be secured in the channel |52 which may engage the chain |56.v

The pulley |51 is connected to the driven shaft of a speed reducer |58 which is in turn driven by a motor |59. As shown, the hearth rotates in the direction of arrow |49 (Fig. 2).

The inner periphery of the hearth 31 is provided with a Y-shaped circular ring which may be of a heat resisting steel and this may be protected from thev intense heat rising in the throat I3 by a lip |60 of refractory bricks.

The sludge drying chamber is provided with a plurality of rabble arms. As shown there are three rabble arms |6I, |62, |63 circumferentially positioned around the path of the rotatable hearth. These rabble arms are mounted in stationary fashion by anchoring their outer ends in suitable clamp holders |64 secured to the side wall of the sludge drying chamber. The rabble arms extend in a substantially radial direction toward the center of the drying chamber and each is provided with a plurality of depending flat rabble teeth or plows. It is to be noted that the rabble teeth lie adjacent the floor of the hearth 31 and teeth |65 of rabble arm |3| and the rabble teeth I 61 of rabble arm |63 are at an angle to move sludge rotating with the hearth inwardly toward the center of the chamber |4, while the rabble teeth |66'on arm |62 are at an angle to push sludge rotating with the hearth outwardly t0- Ward the side wall of the chamber I4. Finally, as the sludge is dried upon the rotating hearth it is moved by the inner teeth of rabble arms 6| and |63 over the lip |60 of the rotating hearth and falls by gravity through the throat |3 of the i'irebox I0 onto the charge |24 so that it will be burned and disposed of there. The ashes ultifmately fall through the grate 4I into the ash pit along with ashes from the burning charge of rubbish.

The sludge to be disposed of and which will ordinarily contain a large amount of waterof the order of 50% to 90%-is charged into the drying zone I4 by means of a screw conveyer |68 mounted to rotate within a charging pipe I 69.'

The sludge is fed through a hopper (not shown) into the pipe |69 and is discharged through the charging port |10 onto the rotatable hearth 31.

The details of suspending the roof are better shown in Fig. Y3. Refractory bricks 32 are hung on small I-beams |13 in turn suspended on horizontal structural steel beams |14 carried above the roof on supporting columns |15. The roof is v provided with a rubbish charging port |16 con-- necting with a chute |11 provided with a sldable closing gate |18 (shown conventionally). The chute is mounted and carried by a rubbish charging floor |79 and the upper end constitutes a hopper |80 when the gate |18 is closed. The hopper has a cover which may be opened o1' closed as desired for charging rubbish from the rubbish charging door |16 into the hopper |00.

A modified form of sludge charging arrangement is shown more or less diagrammatically in Fig. '7. It has an endless belt conveyor 200 for sludge, trained over a cylindrical roll 20| mounted for rotation on an axle 202. The belt is mounted to charge sludge from the conveyor into a chute 203 which extends through the roof ld ofthe sludge charging chamber I4a. A scraper 204 mounted on the end of a pivoted lever 205 will scrape the sludge from the conveyor and the.

sludge will fall into a charging chute 203 into the sludge drying zone onto the rotating hearth 31a. In this case, the screw conveyor and pipe are not used. The chute is substantially sealed off from the outside atmosphere by a Steel plate 206 having a hinged door 20'i, it being noted also that there is provided a gate 203 of flexible material such as rubberized asbestos'having one end 259 fastened to the plate 206 and the other free end resting on the belt and another such flexible piece 2 l il sec-ured to the chute and scraper 204.

The combination sludge and rubbish disposal apparatus described in the foregoing may be 0perated as follows:

Rubbish which may include waste paper, or

other combustible material or garbage and such other similar waste having combustible matter in it, is charged to the hopper |00 and the charge gate |16 is opened to form a pile of charge on the hearth 40 in the rebox. The stuff is set on fire and the furnace warmed up and this may L o be further aided by burning auxiliary fuel in the burner When the operation gets under way the stoker 42 is put into operation, and air is drawn through the heat exchanger 26 to preheat it, Air is drawn or otherwise forced through conduit 6l. Part of it is directed into the ash pit or grate air chamber 43 and passes up through the grate 4| to aid the combustion of the rubbish and charge |24 which is moved outwardly from the pile by the rotating stoker arms |20. Another part of the air, depending upon the adjustment of dampers 'i4 and l5, is passed through conduits 58 and 0l, thence through ports 8|, 82, 33 and 84 into stoker air chamber 80. This preheated air then passes up through spider sleeve |06 where it is again divided. One part of this air flows through the rotating Stoker dome |04 thence through the Stoker arms |20 through air ports |23 into the pile of charge. This air aids combustion and also serves to dry out any moistiu'e in the pile of charge |24. The other part flows up into the Christmas tree tuyre head and out the annular air ports |0l, |02, |03 into the pile of charge, further to dry it out and air combustion. Y

In the meantime sludge or sludge cake is charged into the sludge drying zone through port |70 by the screw conveyor, and falls onto the oor 50 of the rotating sludge hearth 3l which is rotated by means of the motor |59 and its associated mechanism, hereinbefore described. Flame from the burner Ill sweeps around the floor of the hearth and dries out the sludge, the sludge being agitated by the rabble teeth. The hearth rotates in the direction of arrow |49 (see Fig. 2) and rabble teeth |61 and |65 move the sludge inwardly toward the center and teeth |6t` move it outwardly. Finally the dried sludge is gradually moved inwardly over the lip |60 of the rotating hearth into the throat |3 of the flrebox l0 where the dried sludge falls by gravity onto the charge |24. Here it is combined with the rubbish and the combined charge is ultimately completely burned to ashes. It is to be understood that as the outer edge of the pile of charge of rubbish and dried sludge is moved gradually out onto the grate 4| it is completely consumed there. The ashes fall through the grate into ash pit 43 and ,may be removed from time to time through the discharge gate 46 in the ash discharge chute 41. Y

Once the furnace gets under way the i'lrebox is kept charged with rubbish and with sludge to utilize as little as possible of auxiliary heat supplied by fuel burned in burner Ill. In cases where there is sufficient combustible in the charge the intense heat rising through the throat may be suicient to handle the sludge without auxiliary iuel. And it is particularly signiiicant to note also that by reason of the open throat I3 and the intense heat from the dame in rebox I0, there will be a large amount of radiant heat thrown from the flrebox upon the refractory 32 of the roof o'f the sludge drying chamber I4. In turn this hot roof surface heated in part by radiant heat from the firebox I0 will cause radiant heat to be directed on to the rotating hearth 3l. This greatly adds to the efliciency of the apparatus. Y Inasmuch as the chimney provides a draft, air may be drawn from the atmosphere through the port 2l in steel casing I8 into annular chamber 36, thence through the annular passageway 35' into sludge drying chamber I4. Air so drawn in will cool the undercarriage mechanism of the sludge hearth 3l.

Such combustible gases as are distilled off and not consumed in the iirebox or sludge drying zone are ultimately burned in the combustion chamber 20. The hot combustion gases from the combustion chamber pass through the breeching 25 in contact with the air flowing through the heat exchanger 26 to preheat the air passing to the furnace. If the chimney does not provide sufficient draft, air may be forced through the heat exchanger by a blower (not shown). The gases then flow up the chimney (not shown). Obnoxious odors are eliminated by reason of the complete combustion of all combustible material. Accordingly, the plant will not cause an odor nuisance in the vicinity where it is installed.

Moreover, the plant is particularly advantageous when considered from the point of View of over-al1 economy because one furnace is suflicient to dispose of sewage sludge alone or rubbish alone or both; thus eliminating the necessity of a separate installation for each which may otherwise be necessary. Furthermore, the plant is suiciently exible that both sludge and rubbish can be disposed of with a minimum expense for labor and auxiliary fuel.

It will be understood also that the furance and the combustion chamber are provided with access doors usually installed in structures of this kind. These have not been shown in detail in the drawings lest they confuse more important parts. Those skilled in the art, however, will readily understand the installation of such access doors.

While a specific embodiment of the invention has been described herein for purposes of illus- 9 tration, it be understood that modifications and changes may be made without departing from the spirit and scope oi the invention comprehended by the annexed claims.

What is claimed is:

l. An incinerator furnace for disposal of sewage sludge, rubbish and the like which comprises a firebox, a stationary annular hearth in the lower part of the rebox, a grate surrounding said hearth, an ashchamber beneath said grate, a mechanically driven rotatable stoker adjacent said hearth, means dening an. opening at, the upper end or? said rebox providing a throat, a sludge drying chamber above said nrebox, an annular hearth mounted i'or rotation in said chamber and having al central opening registering with said throat, means including a conveyor to charge. sewage sludge to said rotatable hearth, means including a chute to charge rubbish onto said sta-` tionary hearth and rabble means to move sludge on said rotatable hearth intol said central opening to cause the sludge to fall into said reboX, a combastion chamber having flue connection to said rebox and sludgedrying chamber, and means to supply air to said -rebox.

2. An ineinerator' furnace for disposal of sewagesludge, rubbish and the like which comprises a rebox, a stationary annular hearth in the lower part of the rebo-X, a grate surrounding said hearth, an ash chamber beneath said grate, a mechanically driven rotatable Stoker adjacent said hearth, a truncated cone of refractory material open at top and bottom at the upper end of said rebox providing a throat, a sludge drying chamber above said rebox, an annular sludge drying hearth mounted for rotation in said chamber and having a central opening registering with said throat, mechanism tov rotate said sludge drying hearth, means including a conveyor to charge sewage sludge to` said rotatable sludge drying hearth, means including a chute connected with a port in the roof of said sludge drying chamber to charge rubbish onto said stationary hearth and rabble means to move sludge on said rotatable hearth into said central opening to cause' the sludge to fall into said reboX, a combustion chamber having flue connection to said reboX and sludge drying chamber, and means including a heat exchanger and conduit-s to supply air to said iirebox, through said Stoker and said grate.

3. An incinerator furnace for isposal of sewage sludge, rubbish and the like which comprises a firebox, a stationary annular hearth in the lower part of the rebox, a grate surrounding said hearth, an ash chamber beneath said grate, a mechanically driven rotatable Stoker adjacent said hearth, a refractory wall dening an opening at the upper end of said firebox providing a throat, a sludge drying chamber above said rebox, an annular sludge drying hearth mounted for rotation in. said chamber and having a central opening registering with said throat, means including a circular track riding on rollers for rotating said sludge drying hearth, means including a conveyor to charge sewage sludge to said rotatable hearth, means. including a chute mounted above the. roof of said sludge drying chamber to chargeV rubbish through said central opening and throat onto the stationary hearth in said rebox, stationary rabble arms mounted insaid sludge drying chamber, rabble teeth on said arms. to agitate sludge on said rotatable hearth and to urgethe sludge from said rotatable hearth intol said central opening, aburner to I0 supply heat to sludge on said rotatable hearth, a combustion chamber, flue connection between said combustion chamber, nrebox and sludgev dry-y ing chamber, and means to supply air to said irebox.

fr. An incinerator furnace for dispos-al of sewage sludge, rubbish and the like which comprises a cylindrical rebox, a stationary annular hearth in the lower part of the rebox, an annular grate surrounding said hearth, an. ash cham-ber be-` neath. said grate', a mechanically driven rotatable Stoker adjacent sai-d hearth, a refractory wall defining an opening at the upper end of said nrebox providing a throat, a sludge drying chama ber above` said irebox, said sludge drying chain'- ber having a cylindrical side wall. and roof, said roof having a rubbish charging port, an annular hearth mounted for rotation in said chamber and having a central opening registering with throat providing communicationbetween sludge drying chamber and rebox, means including a conveyor to' charge sewage sludge onto said rotatable hearth, means including a stationary openable; and closablechute mounted above said roof and registering with said through said central opening and throat, rabble .mounted in the side walls of: said sludge drying chamber, teeth mounted on said rabble arms, and positioned to agitate sludgey on said rotatable hearth and to urge it into said central opening and thereby cause it tot fall through said throat into said rebox, means including a. passageway between said rotatable hearth and said throat 'for' the passage or air to cool' the underside ofv said rotatable hearth, a combustion chamber having flue connectionv tov said rebox and sludge drying chamber and means to supply air to said reboX.

5. Apparatus for. incinerating sewage sludge and rubbish which comprises a fireboX, a stationary hearth having a central opening with-in the lower part of the rebox, an annular grate adjacent the outer periphery or said stationaryhearth, an ash chamber below-`4 said grate, a

' rotatable stoker having a rotatable shaft ex-Y tending through said central opening and stoker arms extending outwardly to` sweep over said stationary' hearth., means d'e'ning' an opening in the upper end of said' rebox providing a throat,

a sludge drying chamber' above saidV firebox and' connecting therewith, an annular hearth having a centraly opening in registry with said throat and mounted for rotation within said sludge drying chamber, means including a conveyor to charge sludge onto said rotatable hearth, rabblearms having rabble teeth in said sludge drying chamber mounted abovesaid rotatable hearth to urge sludge on said rotatable-hearth into' its said central opening and thereby cause the slu'dge to fall into said iir'ebox, a rubbish charging port above the central opening of said rotatable hearth, a combustion chamber connected" to said' rebox and to said sludge drying chamber', and' means including. conduits to supply air to said rebox through said Stoker and through said grate.

6. Apparatus for incinerating, sewage sludge and rubbish- Which comprises a rlrebox, a station-Y ary hearth. having. a central opening, within the lower part of the firebox an annular grate ad. jacent the outer periphery or saidY stationary hearth, an ash chamber below said. grate, a rotatable stoker having arotatable hollow shaft extendingv through. said central opening and arms extending outwardly to sweep over said stationary hearth, a bevel ring gear secured to the lower end of said hollow shaft, a pinion meshing with said ring gear, a drive shaft secured to said pinion, a closure pipe for said shaft mounting bearings for said shaft, said shaft serving as a conduit for lubricant to lubricate said bearings and pinion, means defining an opening at the upper end of said rebox providing a throat, a sludge drying chamber above said firebox and connecting therewith, an annular hearth having a central opening in registry with said throat and mounted for rotation within said sludge drying chamber, means including a conveyor to charge sludge onto said rotatable hearth, rabble arms having rabble teeth in said sludge drying chamber mounted above said rotatable hearth to urge sludge on said rotatable hearth into its central opening upon rotation of the rotatable hearth and thereby cause the sludge to fall into said rebox, an openable and closable rubbish charging port above the central opening of said rotatable hearth, a combustion chamber connected to said rebox and to said sludge drying chamber, and means including conduits to supply air to said irebox through said stoker and through said grate.

'7. Apparatus for incinerating sewage sludge and rubbish which comprises a flrebox, a stationary hearth having a central opening within the lower part of the rebox, an annular grate adjacent the outer periphery of said stationary hearth, an ash chamber bellow said grate, a rotatable stoker having a rotatable shaft extending through said central opening, and arms extending outwardly to sweep over said stationary hearth, means defining an opening at the upper end of said rebox providing a throat, a sludge drying chamber above said firebox and connecting therewith, an annular hearth having a central opening in registry with said throat and mounted for rotation within said sludge drying chamber, a screw conveyor to charge sludge onto said rotatable hearth, a plurality of radially disposed Stationary rabble arms having rabble teeth, said arms being mounted in the side wall of said sludge drying chamber, said teeth being in the path of travel of sludge on said rotatable hearth and arranged to cause said sludge to move into the central opening of said rotatable hearth and fall into said frebox upon rotation of said rotatable hearth, an openable and closable stationary rubbish chute above said sludge drying chamber through which rubbish will fall onto said stationary hearth, a burner arranged to throw its flame over the path of travel of sludge on said rotatable hearth, a combustion chamber, flue connection between said combustion chamber, rebox and sludge drying chamber, and means to supply air to said rebox.

8. Apparatus for incinerating sewage sludge and rubbish which comprises a iirebox, a stationary hearth having a central opening within the lower part of the lreboX, an annular grate adjacent the outer periphery of said stationary hearth, an ash chamber below said grate, a rotatable stoker having a rotatable shaft extending through said central opening and stoker arms eX- tending outwardly to sweep over said stationary hearth, means defining an opening at the upper end of said frebox providing a throat, a sludge drying chamber above said rebox and connecting therewith, an annular hearth having a central opening in registry with said throat and mounted for rotation within Vsaid sludge drying chamber,` means including a conveyor to charg sludge onto said rotatable hearth, rabble arms having rabble teeth in said sludge drying chamber mounted above said rotatable hearth and disposed so as to urge the sludge through the central opening of the rotatable hearth to cause the sludge to fall into said nrebox, an openable and closable rubbish charging port above the central opening of said rotatable hearth, a combustion chamber connected to said iirebox and to said sludge drying chamber, an upper flue connecting said sludge drying chamber to said combustion chamber, and a lower flue connecting said rebox to said combustion chamber, means including conduits to supply air to said firebox through said stoker and through said grate, and a burner arranged to direct its name in the path oi travel oi sludge rotating with said rotatable hearth.

9. Apparatus for incinerating sewage sludge and rubbish which comprises a rebox, a stationary hearth having a central opening within the lower part of the rebox, an annular grate adjacent the outer periphery of said stationary hearth, an ash chamber below said grate, a rotatable stoker having a rotatable shaft extending through said central opening and stoker arms extending outwardly to sweep over said stationary hearth, means defining an opening at the upper end of said rebox providing a throat, a cylindrical sludge drying chamber above said rebox and connecting therewith, a sludge drying hearth having an annular floor area in which there is a central opening in registry with said throat, said hearth being mounted for rotation within said sludge drying chamber, means including a conveyor to charge sludge onto said rotatable hearth, stationary rabble arms mounted in said sludge drying chamber having rabble teeth positioned above said rotatable floor area in the path of travel of sludge on said area and disposed so as to urge the sludge through the central opening of the rotatable hearth to cause the sludge to fall into said rebox, a burner mounted to direct its flame in the path of travel of sludge on said area, an openable and closable rubbish charging port above the central opening of said rotatable hearth, a combustion chamber, an upper nue having a damper connecting said sludge drying chamber to said combustion chamber and a lower iiue having a damper connecting said rebox to said combustion chamber, and means including a preheater and conduits having adjustable dampers therein to supply air through said Stoker and grate and thence through said iiues.

l0. An incinerator furnace for disposal of sewage sludge, rubbish and the like which comprises a nrebox having a throat in its upper part, a hearth in said firebox to support a charge of material to be burned in said furnace, a grate adjacent said hearth, stoker means to stoke a charge of material on said hearth, an ash pit beneath said grate, a drying chamber above said rebox, a rotatable hearth having an annular floor within said drying chamber, means including a circular track beneath and secured to said floor, said iioor having a central opening registering with said throat, a plurality of rollers supporting said floor forrotation about the aXis of said central opening, driving mechanism to rotate said floor, means including a charging port through which to charge sludge to said floor, rabbling means in the path of travel of sludge on said oor to rabble said sludge and urge it into said central opening and thereby cause it to fall through said throat into said rebox, a chute to charge rubbish into said flrebox, said chute being suspended independently of said furnace and located above said central opening and throat so that rubbish charged therethrough will fall into said rebox, a combustion chamber, flue connection between said combustion chamber and furnace, and means to supply air to said rebox.

11. An incinerator furnace for disposal of sewage sludge, rubbish and the like which comprises a rebox having a throat in its upper part, a hearth in said rebox to support a charge of material to be burned in said furnace, a grate adjacent said hearth, stoker means to VStoke a charge of material on said hearth, an ash pit beneath said grate, a sludge drying chamber above said rebox having a roof, cylindrical side wall and annular bottom closure, a rotatable hearth in said sludge drying chamber having an annular floor, means including a circular track beneath and secured to said floor, said floor having a central opening registering with said throat, a plurality of rollers supporting said oor for rotation about the axis of said central opening, driving mechanism to rotate said floor, a screw conveyor to charge sludge to said oor, a plurality of radially mounted stationary rabble arms in said sludge drying chamber, rabble teeth secured to said arms in the path of travel of sludge on said floor to rabble said sludge and urge it into said central opening and thereby cause it to fall through said throat into said lrebox, means defning a rubbish charging port in said roof, a chute to charge rubbish into said firebox, said chute being suspended independently of said furnace and located above and in line with said charging port, central opening and throat so that rubbish charged therethrough will fall into said rebox, a passageway between the underside of said rotatable hearth and said throat for the passage of air from the atmosphere into said chamber to cool the underside of said rotatable hearth and its associated parts, a combustion chamber, flue connection between said combustion chamber and furnace, and means to supply air to said rebox.

12. An incinerator furnace for disposal of seW- age sludge, rubbish andthe like which comprises a firebox, a stationary annular hearth in the lower part of the firebox, a grate surrounding said hearth, an ash chamber beneath said grate, a mechanically driven rotatable stoker adjacent said hearth, means defining an opening at the upper end .of said rebox providing a throat, a sludge drying chamber above said rebox, an annular hearth mounted for rotation in said chamber and having a central opening registering with said throat, said chamber having a'roof of refractory material overlying said rotatable hearth, means including a conveyor to charge sewage sludge to said rotatable hearth, means including a chute to charge rubbish onto said stationary hearth and rabble means to move sludge on said rotatable hearth into said central opening to cause the sludge to fall into said firebox, a combustion chamber having flue connection to said firebox and sludge drying chamber, and means to supply air to said rebox, said throat permitting radiant heat from material burning in the firebox to pass through said throat to said refractory roof from which roof radiant heat passes to said rotatable hearth.

13. An incinerator furnace for disposal of sewage sludge, rubbish and the like which comprises a rebox, a stationary annular hearth in the lower part of the rebox on which to burn the rubbish, a grate surrounding said hearth, an ash chamber beneath said grate, stoker means to stir rubbish on said hearth, means defining an opening at the upper end of said rebox providing a throat, a sludge drying chamber above said firebox, an annular hearth mounted for rotation in said chamber and having a central opening registering with said throat, said chamber having a roof of refractory material overlying said rotatable hearth, means including a conveyor to charge sewage sludge to said rotatable hearth, means including a chute to charge rubbish onto said stationary hearth and rabble means to move sludge on said rotatable hearth into said central opening to cause the sludge to fall into said rebox, a combustion chamber having flue connection to said rebox and sludge drying chamber, and means to supply air to said i'lrebox, said throat permitting radiant heat from material burning in the lrebox to pass through said throat to said refractory roof from which roof radiant heat passes to said rotatable hearth.

WARREN S. MARTIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 551,342 Wentworth Dec. 10, 1895 647,432 Whedon Apr. 10, 1900 2,171,538 Black Sept. 5, 1939 FOREIGN PATENTS Number Country Date 6,242 Great Britain Apr. 12, 1889 269,331 Italy Nov. 16, 1929 

